Russia and China joined other world powers Friday in condemning Iran over its nuclear program and demanding that Iran freeze nuclear activities.

The unusual show of unity on Iran by the biggest powers of the UN nuclear watchdog agency's board of governors does not guarantee that the road is cleared to a fresh round of economic sanctions on Iran. China in particular maintains that its distaste for sanctions has not changed and that it continues to favor resolution of the Iran crisis through dialogue.

In any case, Iranian officials said no amount of international pressure or number of threats would deter their country's nuclear advances, while some UN officials warned that the verbal reprimand of Tehran might simply reinforce Iran's nuclear hardliners.

The only certainty seems to be that Iran will remain at the top of the world's priorities: President Obama's deadline of the end of the year for Iran to respond to international offers of negotiations is just weeks away.

The chief US envoy to the IAEA, Glyn Davies, called the vote by the six a "significant development," noting that such unanimity on the Iranian issue had evaded the principal powers in the past. Echoing recent words from Mr. Obama, Mr. Davies said the US "remains firmly committed to a peaceful resolution to international concerns over Iran's nuclear program," but "our patience and that of the international community is limited."

On Friday, the White House also issued a statement noting that Friday's IAEA vote "demonstrates the resolve and unity of the international community with regard to Iran's nuclear program.... Indeed, the fact that 25 countries from all parts of the world cast their votes in favor shows the urgent need for Iran to address the growing international deficit of confidence in its intentions."

The IAEA vote came a day after the agency's departing director general, Mohamed ElBaradei, told the governing board that Iran had thwarted IAEA efforts to investigate the status and operations of the Iranian nuclear program. In uncharacteristically stark terms, he concluded that, as a result, agency efforts had "reached a dead end."

Iran maintains that its nuclear program is solely for peaceful power-generation purposes, while the US and European powers say a number of the country's facilities and research projects are consistent only with nuclear-weapons development.

The resolution for censure demands that Iran immediately suspend work on an uranium enrichment site that first came to the world's attention in September. Diplomats at the IAEA say overwhelming passage of the resolution signals mounting frustration with Iran over its rejection of an agreement reached in October under which most of Iran's enriched-uranium stockpile would be shipped out of the country for further refinement.

Prospects that Iran would reverse course and accept that plan dimmed after Friday's vote, when Iran's delegate to the IAEA, Ali Asghar Soltanieh, declared that the resolution would "damage the existing environment of cooperation with the IAEA." He added obliquely that Iran would now cease all "voluntary gestures" toward the nuclear agency.